A known method for flamme fancy yarns manufacture is disclosed in USSR Author's Certificate No. 133,791 in which staple fibres of small length in the form of a sliver are drawn by a drafting apparatus, designed for drawing a sliver from long staple fibres. The sliver breaks and forms flamme effects, the latter being fed to the core thread obtained from long staple fibres simultaneously with the flamme (slub) effects. The thus obtained flamme effects are bound to the core thread by twist. The ready-made yarn is wound onto a bobbin.
The well known method is performed by a conventional drafting apparatus on a spinning machine or a flyer.
The disadvantage of the known method and apparatus are that only short staple fibres can be used for obtaining flamme effects, as the staple length is always considerably smaller than the length of the fibres of the core. The change of the number of flamme effects as per a given length of the ready-made yarn, in accordance with preliminary degree of draft alters the linear density of the core thread.
In USSR Author's Certificate No. 133,791 a device is shown for obtaining flamme fancy yarns, comprising a drafting apparatus with two zones, in which the upper cylinder of the intermediate pair of drawing rollers has a surface, part of which is formed by cylindrical and flat section in succession, thus allowing periodical drawing and breaking of the fed sliver. Binding means for the flamme effects binding to the core thread is provided, as well as a winding unit.
A disadvantage of the known device is that the number of flamme effects in a given length of the ready-made yarn, as well as their length are limited by the form of the surface of the upper cylinder, as the surface does not allow great variety of effects. Thus, for achieving different in size and frequency effects within the limited possibilities of the device, a design of expensive complete upper cylinders is necessary, as additional labour and time consumption is needed for their replacement as per each type of yarn.